1. Technical Field
The present disclosure is directed generally to fireproofing and, more particularly, to intumescent fireproofing systems and methods that generate and release reduced levels of volatile organic compounds (VOCs) and exhibit improved performance characteristics.
2. Background Art
Fireproofing is used in a variety of construction settings to provide fire retardation and thermal protection in the event of a fire. While a variety of techniques have been used to apply fireproofing, fire resistant and/or fire retardant materials in the course of construction, a common method consists of spraying or otherwise applying a fireproofing material onto combustible or heat-sensitive surfaces, e.g., wood, foam insulation, structural steel, floors or walls, to protect such surfaces from fire and heat. It is frequently necessary to apply multiple coats of a fireproofing material to achieve desired levels of fire retardation and/or to comply with applicable building codes.
It is well known in the industry that intumescent fireproofing materials are useful and effective in protecting combustible or heat-sensitive surfaces. Specifically, a significant characteristic of intumescent materials is that they swell or expand into a thick foam char as a result of heat exposure, resulting in increased volume and decreased density. The thick foam char is a poor conductor of heat and thereby possesses heat-insulative and fire-retardant properties. The heat activated reaction causing the expansion of thick foam char also typically generates inert gases, e.g., nitrogen, carbon dioxide, etc., which are entrapped in the foam and, thus, prevent or inhibit air access to a combustible surface. Because the original intumescent coating expands substantially to many times its original thickness, the thick foam char contributes meaningful insulation to the combustible or heat-sensitive surface and may serve as an effective fireproofing agent.
Typical intumescent compositions are shown at “http://perstorp.com/uploadlcharmor_eng—2011.pdf” and “http://www.arkema-inc.com/literature/pdf/864.pdf” Intumescent compositions generally contain a series of basic ingredients (and potentially additional ingredients) as described herein. A resin is generally included and employed to hold the coating together. A coalescent is generally included to aid in the film formation of the resin. A phosphate, such as ammonium polyphosphate (APP) or melamine pyrophosphate, is included and employed to provide (i) expansion gases, (ii) phosphorus acids to decompose carbon-containing chemicals, and (iii) a resultant phosphorus-containing structure to the char. Sugars, such as pentaerythritol or dipentaerythritol, are included and used as carbon-containing chemicals providing structure to the intumescent foam. A chemical, such as melamine, is generally included and used to generate gas during a fire, providing for char expansion. Inorganic solids, such as titanic, are generally included and used for char stabilization. An exemplary ratio for APP/pentaerythritol/melamine/titania of approximately 3:1:1:1 is known to provide an effective intumescent composition.
However, there are opportunities for improvement with respect to intumescent fireproofing materials currently utilized in the industry. For example, intumescent fireproofing materials currently utilized in the industry include constituents that release volatile organic compounds (“VOCs”) during and/or after application, and/or when exposed to heat/fire conditions. VOCs are organic chemicals, often toxic and odiferous, which have boiling points resulting in significant vaporization/release from the liquid or solid state. As a result, undesirably large quantities of VOCs may be released from conventional fireproofing materials. As is well known, some VOCs have been found to cause harmful long-term health effects to humans and are harmful to the environment. Thus, it would be desirable to reduce and/or eliminate the potential for VOC release when developing intumescent fireproofing formulations.
However, the potential elimination of constituents that release VOCs from intumescent fireproofing formulations raises a host of related issues. In particular, the overall performance and commercial viability of intumescent fireproofing compositions require materials that simultaneously yield acceptable thermal performance and application characteristics. Indeed, in the absence of acceptable thermal performance, a proposed intumescent fireproofing formulation is not worthy of consideration.
In terms of application characteristics, one metric by which intumescent fireproofing compositions are measured is “hangability”, i.e., the degree to which the intumescent fireproofing composition remains in a desired application location without undue dripping, sliding, sagging or migration. If an intumescent fireproofing composition exhibits poor hangability, the use of such material may require the application of “thinner” coats to mitigate the inherent hangability limitations of the composition. Specifically, “sagging” refers to situations where the intumescent fireproofing coating moves downward within a desired coating area, whereas “sliding” refers to situations where the intumescent fireproofing coating moves downward below a desired coating area. Among the implications of an intumescent fireproofing composition that exhibits poor hangability characteristics is thin, non-uniform thickness build of the intumescent fireproofing coating, diminishing the surface appearance of the coating, and potentially creating insufficient and uneven fire protection to the combustible or heat-sensitive surface coated.
Moreover and as is well known to persons skilled in the art, the economics of intumescent fireproofing operations are strongly influenced by the thickness that may be applied in a single coat and the degree to which the intumescent fireproofing material may be relied upon to remain in a desired location, i.e., not drip, slide, sag or otherwise migrate to an unacceptable degree. Poor hangability has a clear negative effect on the noted economics because thinner individual coats must be employed, requiring more total coats to achieve requisite fireproofing performance with a concomitant investment of time and expense. Still further, uneven fireproofing thickness may result in thermal failure, thereby undermining the fundamental purpose of the intumescent composition. In addition, uneven fireproofing thickness results in an unacceptable visual appearance, further undermining the beneficial attributes associated with high quality intumescent products. Indeed, an important attribute of commercially viable intumescent compositions is the delivery of a substantially smooth visual appearance when applied to a substrate.
A further issue encountered in the formulation and use of intumescent fireproofing materials is the characteristic of a strong and generally unpleasant odor associated with conventional intumescent products. The elimination and/or masking of such odors would be beneficial to the fireproofing field.
Thus, a need exists for intumescent fireproofing compositions that substantially decrease and/or eliminate the potential for VOC release while simultaneously exhibiting requisite fireproofing properties, including superior thermal performance, desirable hangability properties, and a substantially smooth visual appearance. It is further desired to provide an intumescent fireproofing composition that decreases and/or eliminates the unpleasant odor associated with conventional intumescent fireproofing materials. These and other needs are addressed by the present disclosure.